


Gold Stallion Gym

by Miellat_II



Category: Original Work
Genre: Anal Fisting, Anal Training, Ball Inflation, Bimbofication (male), Body Modification, Body building, Castration, Conditioning, Corruption, Enemas, Equestrian, Equestrian Kink, Erotic Gym, Fucking Machines, General Weird Kinks That Don't Have Names, Gym Sex, Gyms, Hetero-into-homo, Inflation, M/M, Nipple Torture, Prostate Inflation, Pseudomagic, Somnophilia, The Machine - Freeform, Transformation, Vibrators, anal gape, belly inflation, dub-con, electrostim, pony training, slight 'no homo' culture (it IS a gym), urethral Penetration, weight-lifting
Language: English
Status: Completed
Published: 2019-02-22
Updated: 2019-03-19
Packaged: 2019-11-04 01:03:42
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 2
Words: 3,839
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17888597
Author URL: https://archiveofourown.org/users/Miellat_II/pseuds/Miellat_II
Summary: One of the most heteromasculine fronts hides a secret conversion process, headed by a mysterious man. But why does he want to recruit muscleheads and make them into brainless bottoms?





	1. Gold Stallion Gym

**Author's Note:**

> For Diva, who encouraged me to write and post this idea.

The gym had private training rooms for nude training, and advertised full-body training with a personal trainer, sessions lasting all afternoon, one to five.

He signed up, and showed up despite his nerves, the trainer patiently correcting his form so he wouldn’t injure himself, and each hour was broken up with massage. He was surprised how comfortable he felt. His trainer was in red leggings with black contour stitching, and a sleeveless compression shirt to match. He was very defined, but not dehydrated—he lectured shortly on hydration and electrolytes being important, before they started, and pushed his trainee to drink regularly between sets.

It was warm inside the room, and sweat rolled down his skin as he pumped iron. The leg machine was like none he’d ever seen, he was curious about it, but the lower body was the latter half of the training session. They started with feet, lunges and stretches and rolling specifically designed for that, then transitioned to calf strength and training, then worked up to thighs.

He climbed into the leg machine for the thigh work, it was one of the machines that nobody really ever wanted to use in a public space, since you basically squeezed your legs together and then apart, while sitting. Not a flattering pose, but it was really the only way to work those muscles. The only problem was, his kit was definitely going to be in the way.

‘Oh, we can do something that will get it out of the way,’ his trainer said, and knelt down to do something with the machine’s workings.

‘Be careful, dude, that’s delicate…’ he said, trying to laugh it off but more than a little nervous about putting his cock near all this hinged metal. The trainer smiled.

‘No worries, brah, I’ll be careful,’ the trainer said, with that winning, easy smile of his. He pulled something up. ‘You wanna try our signature challenge? It’s really hard, but I think you can do it.’

He was encouraged by that; this gym had a really good reputation. ‘Yeah, definitely!’

‘All right!’ the trainer said, grinning. ‘Just get yourself hard, and slide in here.’

‘Really?’

‘Yeah brah, look, it’s not gay. The endorphins just help the muscles build faster. Your body ignores the pain, like, uh, like a natural painkiller, or something. I’m not a scientist but like, that’s how our guy explained it.’

‘Oh yeah, cool, okay.’

The trainer, politely, turned his back, and gave his trainee some space to stroke his cock. It came up hard pretty quickly, and after sticking a finger into the place he was supposed to stick his cock—just for peace of mind—he found it squishy, soft, and snug, kind of like a sleeve. It probably was a sleeve, really. It was a little awkward to slide in, but the machine wasn’t locked down, and the part moved with him. It was padded on the parts that would touch his hips, and he pulled it all the way down, settling it comfortably. ‘Okay.’

The trainer turned around. ‘Okay, cool!’ He checked the fit, locked something, and then they started again.

‘Oh, damn, this _is_ harder,’ he said, trying to pull against the resistance while he was hard, and staying hard. The opening of the sleeve was very tight, like a cock ring.

‘You’re doing great, brah! Keep going! We’ll do twenty reps, okay? I think I should take off some weight, so you can get used to it.’ He did so, and then counted. His trainee closed his eyes in effort, trying to focus on his breath, on pulling his thighs together against the weight resistance. But his trainer was right; he didn’t feel any of the burn, just the tingling of his arousal, trapped in the sleeve.

The next day he came in for the same session, and the next, and the next, until it was quite comfortable for him to do the routine of stroking his cock up to hardness and putting it into the machine before doing thigh presses.

‘Okay, I think you’re ready for kegels,’ his trainer said, after a month. ‘You’re doing really good, everything’s building really evenly, but you have those lower core muscles, brah, and you gotta work them too, even though it’s like, maybe a little weird to think about.’

It seemed less weird the more he thought about it. ‘Okay, what do we do?’

‘Here, it’s on the thigh press,’ said the trainer, and his trainee climbed into it. The trainer slid the sleeve down this time, after his trainee had stroked himself to hardness quite automatically, without thinking about whether the trainer was watching. He didn’t seem to be paying attention, really, just checking over the machine, pulling things around, pushing levers that made comfortingly-solid clanks.

‘Okay, here we go,’ and he flipped a final toggle, and his trainee felt something warm and slippery and hard slide right up to his ass. ‘Okay, go. This will calibrate for a minute, and then it can give you the right workout. Come on! Keep going!’

It was… distracting, to keep doing reps with that warm thing against his anus; and it seemed like now that the machine had been turned on, electrically speaking, everything was vibrating slightly. But he pushed through, with the encouragement from his trainer, and his trainer kept pushing him to go a little faster, and a little faster, until he was panting to keep up, and barely noticed when the machine pushed inside him, was too much in the zone to notice how it started to pump in time with his reps, how it started to vibrate stronger, until he could barely feel his body at all, barely feel his cock in the sheath over the buzz of the endorphins.

The trainer subtly pressed a button on the back of the machine, near where he was standing, and activated the C function, and the sleeve started to painlessly detach the cock, sucking it downward into the bowels of the machine itself, which ran through the whole building. All the cocks from their converts were collected this way, labelled with their serial number, and put into the training capsules. Up in the training room, while the trainee was working away, sweat shining slick on his skin, not even noticing his anus was being stretched and accustomed to fucking because he was so busy counting and remembering to breathe, the trainer started making him work his arms in the same way. They wanted him to build up his pecs more than anything, to have huge, soft, rounded tits beneath his nipples.

He was exhausted by the end, his trainer having to feed him water and help him out of the machine. He was too tired to really notice anything, buzzing and high from the exercise, and took direction beautifully. The trainer half-led, half-carried him into a resting room, laying him down and putting on the headphones that had binaural frequencies hidden under the nature sounds and white noise, frequencies that would encourage deep sleep.

-

While he slept, the trainer came in and helped the owner insert a small catheter down the seminal tube, so they could inflate his balls. They grew, swelled, until the trainee’s sac was stretched painfully taut, whereupon the trainer rubbed it with oil and shaved it—and everything around it—clean and bare. Then he rubbed it with oil again. The trainer checked his anus, pink and not yet gaping, but soft, yielding easily. An enema of electrolytes would help balance all the sweat that they’d taken out of him, and the trainer made sure it was a gallon, inflating the plug until the trainee’s beautiful boy pussy was spread wide and he whimpered slightly even in his deep sleep. Good. It would adjust by morning, the trainer was sure.

-

He had dreams of being bloated and full, of being submerged, of un urgent need to go and being unable to run, searching frantically for a bathroom in a house that had nothing of the kind…

-

The trainer massaged his pecs as he slept, and put the nipples in snug suction that turned them flush, but not bruisy. Only then was he let alone with his unnatural sleep. For twelve hours, the trainer watched his enema absorb, until it was time to refill him with another gallon, and stretch his anus wider still. The trainer made sure to rub more oil on his taut ballsac, gently squeezing at the balls within, finding them wonderfully tender. He removed the filling tube, and a casual finger held over the urethral opening was all it took to keep his trainee from being able to wet the bed. He slid a small metal plug in, that had a hilt that hugged the curve of his mons in a plaque that had the word ‘Pink’ on it.

Another twelve hours of sleep, and the second enema of electrolytes was fully absorbed. The trainer gave him a final cleansing enema, and then deflated the plug, using flat hooks to hold the anus wide, thoroughly lubing him up after he was emptied, and removing the suction from his nipples. They were swollen now, and would only get more so as the training went on, the trainer looking forward to it with anticipation. But patience was key.

-

When he woke up, he felt relaxed, and was alone in a spartan but comfortable bedroom. He really had to pee, and he felt something heavy and warm between his thighs, which had splayed out in the night. When he sat up and pulled off the sheet, he saw his balls had swelled to the size of peaches, red and shiny, pulling the skin of his sac taut. And his cock was… gone, replaced with a metal plaque with ‘Pink’ stamped into it. His bladder was so full it bulged, and his hips felt… loose, and warm. He found a shower behind the only other door, and tried to take the plaque off, finding it was attached to a plug. Without his cock, he couldn’t aim anything, and peed in the shower, turning it on to take a shower. The gape of his urethra just… coming out of his bare hips like that was disturbing, and the only way he could figure out to cover it up was putting the plug back in.

His balls were _heavy_ , and he stood bow-legged as he showered, washing his hair before wondering if he could come by playing with his balls, since they were more sensitive. He tried it, caressing them, rolling them in both hands (because they were too big for one, now), and the plug in his urethra felt weirdly good as he did so, better and better the more vigorous he was, until he was pulling desperately, and came in a way he’d never felt before, his anus contracting, pulsing, feeling strangely devoid of satisfaction. He took the plug out and tried to come again, but it was even worse, and he dried off and put it back in, his balls still feeling heavy, like they hadn’t come at all.

A huge breakfast was laid out, and he was halfway through it before he realised his muscles didn’t hurt at all—at _all_. That meant he was doing well, right? That he was stronger.

When he finished eating, the trainer came and got him, and acted like nothing was different at all, and the trainee got dressed again—with a little difficulty, glad he had sweatpants to hide his new ballsac—and went home.

-

He went back to train the next day, and the same thing happened. Every morning, he woke up with his balls more and more swollen, and his nipples starting to get more and more pointed and huge. His trainer said the nipples thing happened to most guys, which made sense, given the trainer himself had huge, pointed nipples under that shirt.

His pecs got bigger and bigger, and he found he really liked to massage them and squeeze them. He focussed more on chest building, and on his thighs and hips, because the thigh machine was always the end of his workout—and then, without him really noticing, it was _all_ of his workout, the entire block of four hours spent doing thigh and chest presses on the machine, his trainer working him harder and heavier and faster, and he kept waking up more and more refreshed, even as his balls grew. He decided they were growing because he was getting stronger.

Every time he slept, he dreamed better and better dreams—eating lots of cake at a party, running across the water in some warm sunny place, and floating.

-

The training capsules kept the cocks secure with rods that ran through them, a gentle electric current that could be turned up or down always thrumming, making their owners compliant and disinclined to think too hard. The trainers kept working them, building their leg muscles and their pecs in preparation for their new line of work.

Eventually, the sleep cycle would completely negate any higher brain function, and the morning came for Pink at the same time it did the others.

One morning, he woke up and showered, and ate, and the trainer came in and started to reach for Pink's heavy ballsac, each one the size of an ostrich egg, and Pink didn’t protest, just dully watching like the animal he’d become. The trainer smiled, and so did the trainee in response. The trainer patted and stroked the ballsac.

‘Good boy,’ he said, and clicked a lead-ring around the base of the sac, using the lead-rope to lead the trainee through a different door, into the stables.

He was a good boy! He walked along as the trainer pulled gently on his sac, leading him down a hall with stables on either side, until they went into one. It was too narrow to turn around, and the trainer put the lead-rope into an opening at the back of the stable, and pressed a button that started something pulling gently but inexorably as only a machine could toward the back of the stall. The pony was obliged to walk along, held on tip-toe by the height of the opening. The trainer fastened him into his new feet, which held his natural feet on ballet-pointe, tensing all his leg muscles for a beautiful effect.

The trainer then bent him over, and slid a spreader into his anus. At this point, the pony’s anus was as wide as it could go, and the trainer knew he needed to show the owner that. The lead-rope held the pony’s sac up beautifully, and when the owner came, he fucked the anus himself, his own black-sheathed hand going shoulder-deep, the pony only panting and whimpering in reply, despite not being gagged. The owner liked to test the new ponies, and break them with this treatment. He palpated the pony’s guts over-thoroughly, and the pony was ashen and shaking by the end of it, overwhelmed with the urge to come, but being unable to due to the tightness of the constriction around the base of his sac.

The owner stripped off his glove, admiring the gape of the pony’s anus _now_ , red and unable to close. ‘Gild his insides as well, and I want him in the front-harness—I want to see his pussy gaping when I drive him alongside Aqua. Has he had oral training yet?’

‘No, my lord.’

‘Then start him on it, and sharpish. We have a show in two weeks, I want him with a deep throat bit by then.’

‘Yes, my lord.’


	2. Gold Stallion Stables

The trainer started Pink on his new regimen, piercing his nipples and getting him used to walking in his new feet, pulling him along by the rope-lead around his sac when he hesitated because of the plug in his ass.

‘Come on, boy,’ the trainer would encourage, tugging, watching the urethral plug with Pink’s name on it jostle—doubtless maddeningly—with the movement. He smiled as the pony’s whinnies of distress. ‘Come on.’

Every night, the pony’s bit would be attached to a feeder, and his belly pumped full of food, until it bulged painfully. Then he’d be rubbed down, his belly pressed and massaged, and his bladder allowed to empty, before the trainer gave him his nightly enema and let him lay down in the straw, the urethral plug made bigger and deeper by millimetres at a time, its thick, flexible length quickly reaching his prostate. As soon as it did, the trainer started pumping it.

The pony would be tied down on his back, his legs tied up in the air and his thighs hitched up to pull up his hips and spread to expose them. The trainer would take out all his plugs and clean him by vigorous rubbing with a cloth and hot water, being sure to reach inside the urethra and anus with the rough cloth. Then, he would inject warmed lubricant into the urethra and anus, and use the spreader hooks to winch the anus open to a generous gape, and slide a tapered hose the same width as the nightly plug into the urethra, until it reached the prostate’s opening. Reaching into the pony’s anus would allow the trainer to properly seat the tube’s opening in the prostate’s opening, and the trainer would then being pumping the prostate full, probing it through the pony’s rectum as it grow, coaxing it’s swelling in certain directions, until it filled the pony’s rectum, stretched it, the pressure making it harder and harder. Then, the pony’s distressed cries in the background, the trainer would remove the spreader hooks (which jostled the prostate), and inject an expanding, flexible seal to the prostate’s opening, keeping the pony from being milked, and assuring his prostate would continue to expand, until it was pushed right out of his anus, during an especially agonising night of sleep, and the trainer would come upon it in the morning, hanging down between the pony’s legs, marking him as ready for castration.

Pink was tied down with the strap around his sac, the ever-present strap he’d gotten used to, over the time he’d been in the stable, and his prostate was fondled, making him wince and cry out through the bit filling his mouth and throat. The trainer patted his prostate, watching it gently heave and sway with the pony’s tensing, watching how it dragged the anal opening down with its weight. Pink had been getting used to its presence by now, after a week of its emergence, and the constant tensing and squeezing of the pony’s anus had effectively pushed all the fluid to swell outside, leaving a narrow base for the trainer to attach a band. It was a t-shaped band, that not only constricted the base, but also squeezed down the middle, separating the swollen gland into two halves, so that it more closely resembled a stallion’s balls.

As for the pony’s real balls, the trainer pulled the strap around the base of the pony’s sac down, stretching them taut, and nudged the pony’s legs wide and wider, until he was barely balancing. Then, he put a clamp right up against the pony’s body, and tightened it. This done, he slid a large, blunt metal sphere against the pony’s new balls, making sure to coat the pony in conductive gel first. Finally, he removed the urethral plug, knowing the plug to his prostate would be worn down enough by now.

He turned it on, and the pony immediately felt an electric current to his prostate, and began to scream, unable to move, muscles tensing, gaping urethra gushing with fluid as he came without coming, on and on. He didn’t notice when the trainer closed the shears, when the weight of his old sac was no more. All his attention was on the new one, which was just how the trainer wanted it to be.

After dressing the wound, the trainer turned off the electricity, and was pleased to note that the prostate was still firm. He attached each side to an IV of fluid that would firm up upon setting, making a good weight that could not be depleted.

He rubbed the pony down, checking his nipples, and put him down in the straw to sleep.

The pony healed up very quickly, and his new balls let him run much more easily and with better posture. The harness for the cart spread his anus around a brass ring, and strapped his balls tight and shiny with another, that had a bell on it. Thus his new balls were perfectly positioned to receive direction from the whip. The deep-throat bit went all the way down Pink’s throat, forcing his head up; but tapered toward the end, so that his jaw could close, the harness on his head connected to a neck-corset that held his head up even more, his throat pressed on inside and outside. The reins were attached to rings piercing his fattened nipples, and he was spread wide and held down as a deep, probing tube filled up his entire lower intestine with a thick, hot, heavy fluid, that coated his inner walls in glittering gold. The same gilding was applied to his new balls, before the harness went on.

The Owner came to see him when he was fully ready for the cart, though the trainer had, as was customary, refrained from using the whip on him. His nipples were heavy from the rings and the pulling of the reins, and the plaque with his name was attached to the harness, looking very pretty. The trainer had freshly groomed his hair into a mane, and the pink harness was shining in the sunlight.

He was hitched to the cart, and began to pull, knowing by now that because the harness was attached to his urethral plug, pulling the cart pushed the plug a little deeper, over and over, tickling his insides just right to feel a warm buzz of pleasure. Running also jostled the rings in his nipples, and his balls bounced pleasantly. HE was, therefore, very motivated to keep running and pulling the cart.

He felt a snap to his balls, and cried out in surprise, running to try and escape. Another snap, and he was running faster; a tug to one nipple and he turned toward it to relieve the pressure. Another tug to the other and he turned the other way. A snap to his balls and he pushed on, faster, fast as he could, never able to escape the whip, and too dumb to realise the effort was futile.

He ran, and ran, and felt he had escaped the whip at last, when he felt gentler tugs to both nipples, and slowed down, and felt more tugging, until he was stopped, panting, shining with sweat, his flanks heaving.

‘He does very well; I _do_ think we _have_ found a match for Aqua. How splendid.’

**Author's Note:**

> Want to talk to me and other fans? Come to [my discord](https://discord.gg/uVJR3ad), darling!


End file.
